1. Field of the Invention
This invention relates generally to the field of turbochargers having variable turbine inlet geometries. More particularly, the present invention provides a simplified structural arrangement for positioning multiple aerodynamic vanes in the inlet nozzle of the turbine housing and an integrated actuator for control of the vane position.
2. Description of the Related Art
In a turbocharger it is often desirable to control the flow of exhaust gas into the turbine to improve the efficiency or operational range. Various configurations of variable nozzles have been employed to control the exhaust gas flow. Multiple pivoting vanes annularly positioned around the turbine inlet and commonly controlled to alter the throat area of the passages between the vanes is an approach which has been successfully used in prior turbochargers. Various approaches to this method for implementing a variable nozzle are disclosed in U.S. Pat. No. 4,679,984 to Swihart et al. entitled "Actuation System for Variable Nozzle Turbine" and U.S. Pat. No. 4,804,316 to Fleury entitled "Suspension for the Pivoting Vane Actuation Mechanism of a Variable Nozzle Turbocharger" having a common assignee with the present application.
While multiple vane variable nozzle turbochargers have significantly increased the overall efficiency and capability of turbochargers, the complexity of support and actuation structures for the vanes have increased manufacturing costs and occasionally created maintenance issues. It is therefore desirable to reduce the complexity and parts count of variable nozzle structural arrangements and improve the actuation systems to increase reliability and reduce manufacturing cost for turbochargers employing them.